I can imagine that the possible PS4 will be able to play PS3 games. Lol.

I expect 0 backward compatibility with PS3 games. They'd have to emulate since the CPU is completely different. Maybe the PS4 is powerful enough to emulate, but judging by the amount of PS2 to PS3 emulations we got...don't get your hopes up.

Keep the price of the PS4 at around $399 launch and those who absolutely need to buy a PS3 to play PS3 games can pick one up for $99 later down the road. This would be MUCH preferred over paying $600 launch which includes what was basically a PS2 shoved inside a PS3. Could have just removed the PS2 part and lowered the price of the PS3 a bit.